New discovery of Quaternary normal faulting in the Daju Basin, southeastern margin of the Qinghai-Xizang Plateau: Geometry, kinematics, and seismic hazard analysis of the Jiangbian fault

Objective The Jiangbian fault is an active fault recently identified in the Daju Basin at the southeastern margin of the Qinghai-Xizang Plateau. The analysis of fault activity is of great scientific significance. It can further deepen the geometric structure and kinematic characteristics of the Haba—Yulong Snow Mountain fault zone and understand the tectonic deformation mechanism of this area. Also, it has important application value to the assessment of geological hazards and prediction of seismic activity trend in this area affected by fault activity. Simultaneously, it serves as a foundational study for evaluating the potential for significant seismic events in the eastern foothills of Haba—Yulong Snow Mountain due to fault activity.

Methods This study is based on field satellite imagery and geological surveys conducted in the Daju Basin, Southeastern margin of the Qinghai-Xizang Plateau. It is complemented by previous geochronological research and seismic data collected in the area.

Results Field geological survey and remote sensing interpretation confirm that the Jiangbian fault is a Quaternary active normal fault. The moderate to strong seismicity in the study area is dominated by normal faulting mechanisms, which is broadly consistent with the Late Quaternary kinematic characteristics of both the Haba—Yulong Snow Mountains eastern piedmont fault and the Jiangbian fault.

Conclusions ① A new Quaternary fault, named the Jiangbian fault, has been identified near the eastern foothills of Haba−Yulong Snow Mountain in northwestern Yunnan Province at the southeastern margin of the Qinghai-Xizang Plateau, situated to the west of the Daju Basin. The fault bifurcates into two branches, running approximately 28.5 kilometers in total. It exhibits a general NWW strike and a SW dip, with an inclination angle ranging from 40° to 68°.② The Jiangbian fault is an active normal fault from the late Quaternary period, displaying evidence of at least two periods of activity since that time. The most prominent episode of fault activity occurred approximately 19 ka ago.③ The Jiangbian fault is considered a secondary fault located at the eastern foot of Haba−Yulong Snow Mountain.④ In the study area, moderate and strong earthquake activities are primarily associated with normal faults, indicating a higher likelihood of future occurrences and a greater risk of producing significant earthquakes.